Digital Networks

Telephone line modems are gradually being replaced by digital network cables that connect direct to users’ businesses and homes. These are known as cable modems.

Modems can be connected to the serial, parallel or USB ports.

The serial port is a connection that allows a computer to transmit data to another device using serial transmission. This means one bit at a time. It is common for a computer to be connected to a printer or modem via a serial port. The parallel interface on the back of a computer is sometimes called the printer interface.

A parallel port is a connection that allows the computer to transmit data using parallel transmission, where several bits are sent simultaneously over separate wires. A parallel port may be connected to a printer, in which case the printer will be known as a parallel printer. You should understand the differences between parallel and serial ports and how they are used.

Modern computers also often have a Universal Serial Port (USB). Devices can be connected to this port without switching the computer off first.